This invention relates to electronic language learning aids, teaching machines and electronic training aids. More specifically, this invention relates to electronic language learning aids, teaching machines and electronic training aids having means for producing synthesized speech implemented in a minature semiconductor chip.
The prior art suggests various techniques for synthesizing human speech from digital data. For instance, some of the techniques used are briefly described in "Voice Signals: Bit by Bit" at pages 28-34 of the October 1973 issue of IEEE Spectrum. An important technique for synthesizing human speech, and the technique used by the speech synthesizer chip of the electronic language translator described herein, is called linear predictive coding. For a detailed discussion of this technique, see "Speech Analysis and Synthesis by Linear Prediction of the Speech Wave" by B. S. Atal and Suzanne L. Hanauer which appears at pp. 637-50 of Vol. 50, No. 2 (part 2) of the Journal of the Acoustical Society of America.
In U.S. patent application Ser. No. 905,328, filed May 12, 1978 now U.S. Pat. No. 4,209,844 issued June 24, 1980, a lattice filter for generating digital signals useful in producing synthesized human speech and capable of being implemented on a single semiconductor chip is described. The language translator described herein makes use of the lattice filter described in the aforementioned U.S. Pat. No. 4,209,844.
It is one object of this invention that the language translator be equipped to audibly pronounce desired words in a foreign language.
It is another object of this invention that the language translator be equipped to audibly pronounce a phrase of more than one word in a foreign language.
It is yet another object of this invention that the words and phrases which the translator is equipped to audibly pronounce be randomly accessible.
It is yet another object of this invention that language translator circuits be implemented on a miniature semiconductor chip so that the entire language translator could be simply constructable as a portable device.
The foregoing objects are achieved as is now described. The words and phrases to be pronounced by the electronic language translator are stored as digital codes in a memory device. This memory is preferably of the non-volatile type so that the data is not erased when power is disconnected from the apparatus. A speech synthesizer circuit is connected to the output of the memory for selectively converting some of the signals stored therein to speech signals from which audible speech is generated. Several types of speech synthesis circuits are known. In the disclosed embodiment, of the electronic language translator the speech synthesizer thereof is implemented as an integrated circuit on a single semiconductor chip and employs a linear predictive coding technique in synthesizing speech. A speaker is provided to convert output from the speech synthesizer to audible sounds. A keyboard and display, both of which preferably are capable of accommodating alphanumeric characters, are preferably provided. The display and keyboard are preferably coupled to the speech synthesis circuit and memory via digital logic means in the form of a controller circuit. In the embodiment disclosed, the controller circuit is an appropriately programmed microprocessor device. The controller circuit controls the memory to read out the digital signals corresponding to the words and phrases to be pronounced, the words and phrases preferably being randomly selectable from a plurality of words and phrases stored therein. The digital signals representative of the words and phrases are converted to audible voiced words and phrases by means of the synthesizer circuit in combination with the speaker. The memory also preferably stores numerical data to allow easier access to a given phrase, which data is supplied to the controller circuit. When the operator selects a word or phrase to be pronounced by inputting a word or phrase number at the keyboard, the controller compares the inputted word or phrase number with the words stored in the memory and the operator is informed of the appropriate word or phrase in the foreign language. The operator may be so informed either visually via the display or audibly via the speech synthesis circuit and speaker. The phrases pronounced may be made long and complex by connecting various fragmented phrases available in the memory. Of course, the shorter the phrases pronounced the greater the number of phrases storable in a memory of given capacity. Of course, the particular words selected for any given library are a design choice. The language translator is installed in an easily portable case. The size of the speech synthesis chip included as a component thereof is on the order of 45,000 square mils using conventional MOS design rules and a conventional P-MOS processing technique. Of course, using C-MOS processing would tend to increase the size of the chip somewhat.
In the embodiment disclosed, the translator is preferably equipped with other modes of operation which are described in detail.